JPS6042246A - Glass for substrate - Google Patents

Abstract

PURPOSE:To obtain alkali-free glass for a substrate having superior heat resistance and chemical resistance, suitable for manufacture in large quantities, and useful to form a thin film of a semiconductor, a metal or the like by adding a plurality of specified oxides to high aluminous alkaline earth metallic aluminosilicate. CONSTITUTION:This glass consists of, by mole, 45-60% SiO2, 20-35% AlO3/2, 1-5% ZrO2, 10-25% MgO, 2-10% RO (R is Ca, Ba or Sr) and 2X10<-4>-2X 10<-3>% R'2O3 (R' is As or Sb). The glass belongs to high aluminous alkaline earth metallic aluminosilicate. The heat resistance and chemical resistance are improved by adding ZrO2, and bubble removal and refining are accelerated by adding at least one between As2O3 and Sb2O3. The glass has superior heat resistance and chemical resistance, contains no alkali, and can be manufactured in large quantities at a low cost unlike quartz glass. The glass is suitable for use as glass for a substrate for forming a film of a semiconductor, a metal or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a glass used for a substrate on which various films such as semiconductors and metals are formed.

[Technical background of the invention and its problems]

Thin films of various semiconductors, metals, dielectrics, etc. are currently used in almost all types of electronic components. These thin films are deposited by heating on a suitable substrate.

It is formed by physical methods such as sputtering and chemical methods such as thermal decomposition and photolysis. When such thin films are used in electronics, displays, etc., the substrate must be transparent, and glass substrates are often used because they are inexpensive and easily available.

Incidentally, glass for substrates is required to have the following advanced characteristics in response to the strict requirements of thin film devices.

■ Must not contain alkali. If the substrate glass contains alkali, its ions will diffuse into the formed thin film and deteriorate its properties.

■ High heat resistance. In order to form a thin film with good crystallinity and excellent properties on a substrate, it is necessary to perform the deposition at a high temperature. Further, a heat treatment process at high temperature may be performed. However, the heat resistance of currently available glass for substrates is limited to 500 to 600°C, making them unsuitable for devices that require heat treatment at about 800°C, such as silicon thin film transistors.

■ Excellent chemical resistance. The thin film formed on the substrate is etched using methods such as photolithography to create the desired device, but highly corrosive chemicals such as strong acids and alkalis are used in this buttering process, which may damage the substrate itself. must not be corroded (etched).

Quartz glass has been known as a glass that satisfies the various requirements mentioned above. However, quartz glass requires a special manufacturing method and is therefore extremely expensive. In addition, although it has the characteristic of low thermal expansion, it tends to be a drawback in devices that require bonding or sealing with different materials, for example.

[Purpose of the invention]

The present invention aims to provide a mass-produced alkali-free glass for substrates that has excellent heat resistance and chemical resistance.

[Summary of the invention]

The present invention is 810245~60% ruti, kloi 20~
35 mol%, ZrO21-5 mol%, MgO1
O ~ 25 mol%, RO (However, R is Ca + Ba
at least xi) 2 to 10 mol % of TSr.

R'203 (wherein R' is at least 5 types of Air sb) consisting of 2×10 to 2×10 molti. Glass with this composition belongs to high alumina alkaline earth-aluminosilicate, and has improved heat resistance and chemical resistance by adding ZrO2, and also has As2O5, 5
Defoaming and clarification is achieved by blending at least one type of b205.

Next, the effects of each of the above-mentioned components and the reasons for limiting their blending ratios will be explained.

(i) Si02 SI0213. It is the main component of glass.

When the blending ratio of 5 to 2 is less than 45 molty, chemical resistance decreases, and for example, when concentrated hydrochloric acid is boiled in diluted hydrochloric acid diluted with water at a ratio of 1:1, the surface becomes cloudy. On the other hand, when 5to2 exceeds 60 molti, the high temperature viscosity increases significantly and 16
It becomes impossible to melt at temperatures below 00°C, which poses a problem in production.

(lri AtOs/2 At03/2 also forms the main component of the glass.

If the blending ratio of hto572 is less than 20 moles, the viscosity of the glass increases, making defoaming virtually impossible. On the other hand, Azo3. If z2 exceeds 35 molts, the glass tends to crystallize) and normal molding methods cannot be applied.

(11Dzr02 Zr02 contributes to improving the heat resistance of glass. For example, 5
I02- At2Q5- MgO-Ca glass and low-expansion, heat-resistant glass made by adding ZnO (zinc oxide), etc. to it are known, but in a practical composition range, the glass transition temperature (Tg) is 800°C. Not reached. However, by adding ZrO2 to the above component system, the Tg could be increased to 800° C. or higher without impairing the meltability of the glass. ZrO2 also contributes to improving chemical resistance. These Z
If the blending ratio of rO2 is less than 1 molty, the effect cannot be sufficiently achieved, but if it exceeds 5 molty, the glass tends to devitrify.

ψMgO MgO is an important component in terms of improving heat resistance and the like. Mg
If the blending ratio of O is less than 1θmolt, the effect cannot be fully exhibited, whereas if it exceeds 25molt, the glass tends to devitrify.

(V) RO RO is composed of at least one of CaO, BaO, and SrO, is an auxiliary component of MgO, and contributes to improving meltability. In order to obtain a homogeneous and stable glass, it is necessary to mix 2 or more moles of these components; however, if the amount exceeds 10 moles, the heat resistance of the glass will deteriorate and Tg will not exceed 800°C. . Note that CaO is particularly useful as RO in terms of improving the above characteristics.

) R'O R'O consists of at least one of As2O3 and 5b205, and the blending ratio of these should be in the range of 2 x lθ to 2 x 1 O-3 mole to obtain a homogeneous glass through defoaming and clarification. It is necessary to.

Note that ordinary glass raw materials can be used as they are for the various oxides mentioned above. That is, n-made silica sand.

Aluminum hydroxide, magnesia, zirconia.

Calcium carbonate, barium carbonate, etc. are mixed to a target composition, and then melted and homogenized in an electric furnace.

When using antifoaming agents such as arsenous acid and antimony oxide, some of the ingredients are used in the form of nitrates to make them oxidizing. The glass thus obtained is formed by a roll method, a press method, etc., and polished to obtain a substrate glass.

[Embodiments of the invention]

Next, the present invention will be explained in detail.

Examples 1 to 8 First, purified silica sand, aluminum hydroxide, zirconium oxide, magnesium oxide, magnesium nitrate, calcium carbonate, and strontium carbonate.

Made from barium carbonate, arsenous acid, and antimony trioxide,
These were mixed to produce glasses having the compositions shown in Table 1 below. Note that since As2O3 has a low concentration, the total amount of oxides excluding these is 10.

and added to this. The amounts of the obtained glasses were about 2 kg each, which were placed in a platinum glass and melted at 1450-1550°C in an oxygen-city gas furnace. The time required for defoaming was about 6 hours.

Subsequently, the glass was pressed on an iron plate to form a disk with a diameter of about 100 mm, and then slowly cooled from 850°C.

However, the coefficient of thermal expansion, glass transition point, yield temperature, and chemical resistance of the eight types of disk glasses obtained were investigated.

The results are shown in Table 2.

The coefficient of thermal expansion was measured by cutting out a portion of the glass disk and using an interference expansion needle. Chemical resistance was evaluated by boiling a disk glass whose surface had been polished in dilute hydrochloric acid prepared by diluting conch hydrochloric acid with water at a ratio of 1:1 for 2 hours, and observing the deterioration of the surface.

As is clear from Table 2 above, all the glasses of the present invention have a glass transition temperature of 800° C. or higher, which is a measure of heat resistance, and also have sufficient chemical resistance.

Further, each of the obtained glasses was polished to a size of 100 mm diameter x 1-0, and a silicon thin film was formed by chemical vapor deposition.

At this time, vapor deposition was carried out at a substrate (glass) temperature of 800° C., but there was no deterioration of the substrate, and a silicon thin film having good electrical properties consisting of crystal grains on the order of μm could be formed thereon.

〔Effect of the invention〕

As detailed above, according to the present invention, Tg is 800°C or higher, which is excellent in heat resistance, side chemical resistance is also good, and
It is possible to provide an inexpensive and high-performance substrate glass that can be homogeneously melted at 0° C. or lower and is suitable for vapor deposition of thin films of semiconductors, metals, dielectrics, and the like.

Applicant's representative Patent attorney Takehiko Suzue Kensuke Norichika (
1 person) -288-

Claims (1)

[Claims] 5 to 245 to 60 mol%, A10V220 to 35 mol%, ZrO2j to 5 mol%, 1MgoIO to 25 mol%, RO (where R is Ca, Ba, Sr
at least one of the following) 2 to 10 mol%Os
(However, RI is at least one of As' and Sb.) A glass for a substrate made of 2 x 10-' to 2XIO mulch.